Re: [Pw_forum] problem with phonon calculation

[chaitanya varma]

Dear sir,when i ran the phonon calculation for PbTiO3 with tetragonal structure 
in the output file i got negative frequencies and negative dielectric constant, 
can i know where i did worng.Convergence has been achieved 

 Number of q in the star =    1
 List of q in the star:
  1   0.0   0.0   0.0

  Dielectric constant in cartesian axis 

  (  53.479682169  -4.588399890 -12.973363015 )
  (  -4.588399085  40.178849877   4.029708708 )
  ( -12.973363359   4.029706013  59.207850004 )
Diagonalizing the dynamical matrix

 q = (    0.0   0.0   0.0 ) 

 **
 freq (    1) = -26.415709 [THz] =    -881.133205 [cm-1]
 freq (    2) = -20.796909 [THz] =    -693.710200 [cm-1]
 freq (    3) = -17.827704 [THz] =    -594.668189 [cm-1]
 freq (    4) =  -7.991439 [THz] =    -266.565722 [cm-1]
 freq (    5) =   0.272538 [THz] =   9.090898 [cm-1]
 freq (    6) =   0.904088 [THz] =  30.157139 [cm-1]
 freq (    7) =   1.108034 [THz] =  36.960023 [cm-1]
 freq (    8) =  18.450705 [THz] = 615.449285 [cm-1]
 freq (    9) =  26.323046 [THz] = 878.042300 [cm-1]
 freq (   10) =  44.247850 [THz] =    1475.949412 [cm-1]
 freq (   11) =  57.065006 [THz] =    1903.483720 [cm-1]
 freq (   12) =  58.078593 [THz] =    1937.293337 [cm-1]
 **

 Mode symmetry, C_1 (1) point group:

 freq (  1 -  1) =   -881.1  [cm-1]   --> A   I+R
 freq (  2 -  2) =   -693.7  [cm-1]   --> A   I+R
 freq (  3 -  3) =   -594.7  [cm-1]   --> A   I+R
 freq (  4 -  4) =   -266.6  [cm-1]   --> A   I+R
 freq (  5 -  5) =  9.1  [cm-1]   --> A   I+R
 freq (  6 -  6) = 30.2  [cm-1]   --> A   I+R
 freq (  7 -  7) = 37.0  [cm-1]   --> A   I+R
 freq (  8 -  8) =    615.4  [cm-1]   --> A   I+R
 freq (  9 -  9) =    878.0  [cm-1]   --> A   I+R
 freq ( 10 - 10) =   1475.9  [cm-1]   --> A   I+R
 freq ( 11 - 11) =   1903.5  [cm-1]   --> A   I+R
 freq ( 12 - 12) =   1937.3  [cm-1]   --> A   I+R regards
Chaitanya Varma M  Assistant professorDept of PhysicsGITAM 
UniversityVisakhapatnam, India
 


 On Saturday, 5 September 2015 2:18 PM, dario rocca  
wrote:
   

 Dear Chaitanya
As the error message says you cannot use "occupations=tetrahedra" with the 
phonon code since this approach is not implemented 
The only solution is to use a smearing instead
Best regards,
Dario

On Sat, Sep 5, 2015 at 8:39 AM, chaitanya varma  wrote:

Dear Sir,I am trying to calculate DOS, pDOS and phonon densities etc of PbTiO3 
-(tetragonal structure)SCF, NSCF and BANDS calculations worked out nicely with 
tetrahedra,but while doing ph.x calculation i am getting the following error

 %%
 Error in routine phq_setup (1):
 phonon + tetrahedra not implemented
 %%

 stopping ...
can i know where i am doing wrong.i am attaching the scf.in and phG.in/out files
thanks and regards Chaitanya Varma MAsst ProfessorGITAM UniversityIndia
  
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Re: [Pw_forum] kpoints for transmission calculations and complex band structures?

[Filipe Camargo Dalmatti Alves Lima]

Dear Fang,

Unfornately I don't have any experience with the systems you are
investigating, but I'll add my comments that might provide you some
insights.

The answer for your question is simple but will require some effort to
accomplish it: you must test your system and make sure the properties are
converged.

Convergence means the following: As you increase a given parameter that you
are tracking, the results are not changing anymore.

In order to achieve that for your systems, I would recommend two things:

1) Look for the literature and check the parameters they used the same
systems.

2) Do a series of tests increasing the parameters at a point that the
properties you are investigating are not changing anymore. We all know that
for some systems these tests might be prohibitive (this is why the step 1
is so important). In that case, go for the best grid you can simulate and
honestly note that on the reports. Just to remember you, if the DOS and
total energy are converged, your tests for band structure can be only NSCF.
But please MAKE A BACKUP of your ".save"  folder (if you are using the
wf_collect=.true.) because the NSCF messes up with the restart.


I hope you find at least part of these insights useful.

Best regards,

Filipe






On Sun, Sep 6, 2015 at 8:31 AM, Yue-Wen Fang  wrote:

> Dear all,
>
> For a  junction, e.g. Fe/MgO/Fe MTJ with a=b=2.8, c = 34 angstrom, a
> general DOS  calculation usually require a kgrid as 11*11*1, however, could
> anyone tell me how many kpoints do I need to set for it in transmission
> calculation and complex band structure calculation, respectively?
>
> Thank you in advance!
>
> Bests
> Fang
>
> --
>
> 
> Yue-Wen FANG, PhD candidate
> Key Laboratory of Polar Materials and Devices, Ministry of Education
> 
> East China Normal University  
>
>
>
>
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-- 
_
Dr. Filipe Camargo Dalmatti Alves Lima
Pos-Doc at Materials Physics Department.
University of São Paulo, Physics Institute, Brazil.
Phones:+55 (11) 3091-6881  (USP)
+55 (11) 97408-2755 (Cellphone - Vivo)
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Re: [Pw_forum] DOS Calculation

[Filipe Camargo Dalmatti Alves Lima]

Dear Kanak,

Are you using Windows? I would suggest you delete the outdir line because
there are a lot of specials characters that might be sources of errors.

As default, the result will be written in the same folder you execute the
calculation.

Best,

Filipe

On Thu, Sep 10, 2015 at 8:34 AM, Kanak Datta  wrote:

> Dear researchers
>
> I am facing problems in DOS calculation. I wanted to run the given example
> in reference. I ran example 02 for this. The example is on bulk Ni. I ran
> scf-> nscf and then went for dos.
>
> 
> outdir='D:\QuantumEspresso\Quantum ESPRESSO 64-bit 5.1.2-mpich2\ni'
> prefix='ni'
> fildos='ni.dos',
> Emin=5.0, Emax=25.0, DeltaE=0.1
>  /
>
> I used dos.x package for this. However I am getting the following error:
>
>  Error in routine dos (1):
>  reading dos namelist
>
> I can't figure out what's wrong. Can you help?
> Thanks in advance.
>
> Sincerely yours
> Kanak
> EEE, BUET
>
>
>
>
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-- 
_
Dr. Filipe Camargo Dalmatti Alves Lima
Pos-Doc at Materials Physics Department.
University of São Paulo, Physics Institute, Brazil.
Phones:+55 (11) 3091-6881  (USP)
+55 (11) 97408-2755 (Cellphone - Vivo)
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Re: [Pw_forum] Spin-Orbit Calculation

[Ajit Kumar Jena]

Thanks a lot Roberta for your informative reply.

___
Ajit
On 10-Sep-2015 10:30 pm, "roberta pigliapochi" 
wrote:

> Dear Ajit,
> please bear in mind that I AM NOT AN EXPERT and I would instead really
> appreciate comments from more experienced users. I will try to give some
> advice but take it with a pinch of salt. I would also like to follow up on
> this by asking:
>
> can noncolinear calculations and DFT+U go together now?
>
> Referring to your points:
>
> 1)the AFM initial guess is set up fine. The system might still converge to
> a FM situation, though. If instead you'd rather force it to stay AFM I'd go
> for 'tot_magnetization'
> 2)yes. You may also need to specify lda_plus_u=.true. beforehand.
> 3)I'd say so, and I also think that the 'angle' isn't a fixed value but
> rather will be optimised during the scf. Instead if you'd prefer the two
> (or total) magnetizations to be kept fixed along y I'd go for
> 'constrained_magnetization'
> 4)I think that the default 'domag' (whatever it means) is set to false,
> hence there should be no need for your flag to be there. Also, 'nspin=4'
> may be redundant considering that you have set 'noncolin=.true.'
>
> hope some more hard-core expert will comment on this.
>
> good luck (:
> Roberta
>
> Roberta Pigliapochi
> PhD Student | Grey Research Group
> University of Cambridge
>
>
> On 8 September 2015 at 12:48, Ajit Kumar Jena  wrote:
>
>> Dear All,
>> I wish to do a *spin-orbit calculation* of our system
>> (LiFePO4) which involves iron (Fe) as a magnetic element. Her*e *I am
>> providing my input variables containing the system name lists and atomic
>> species.
>>
>> My questions are the following :
>>
>> 1) As it is mentioned in the input, should I consider two different types
>> of spins ( up and down ) to do a anti-ferromagnetic calculation ?
>> 2) The way I have incorporated Hubbard 'U' is appropriate or not ?
>> 3) If I am giving the inputs in this way, will it take the starting spin
>> quantization axis along Y-direction or not ?
>> 4) Is there any problem if i will not include " starting_spin_angle =
>> .true. " ?
>>
>> Any kind of help is highly appreciated. I am extremely sorry if my
>> questions are very trivial.
>>
>> *Input*
>> 
>> ibrav=  8,
>> celldm(1) = 19.326236,
>> celldm(2) = 0.587151,
>> celldm(3) = 0.458766,
>> nat=  28,
>> ntyp= 7,
>> !nspin = 4,
>> starting_magnetization(2) = 0.7,
>> starting_magnetization(3) = -0.7,
>> ecutwfc =30.0,
>> ecutrho = 250.0,
>> occupations = 'smearing' ,
>> degauss = 0.001 ,
>> smearing = 'gaussian' ,
>> noncolin = .true.
>> lspinorb = .true.
>> starting_spin_angle = .true.
>> angle1(2) = 90.0
>> angle2(2) = 90.0
>> angle1(3) = 90.0
>> angle2(3) = 90.0
>> lda_plus_u_kind = 0,
>> Hubbard_U(2)=3.0,
>> Hubbard_U(3)=3.0,
>>
>> ATOMIC_SPECIES
>>  Li1  6.94  Li.pbe-s-van_ak.UPF
>>  Fe1  55.845Fe.rel-pbe-spn-rrkjus_psl.0.2.1.UPF
>>  Fe2  55.845Fe.rel-pbe-spn-rrkjus_psl.0.2.1.UPF
>>  P1   30.9737   P.pbe-van_ak.UPF
>>  O1   15.999O.pbe-van_ak.UPF
>>  O2   15.999O.pbe-van_ak.UPF
>>  O3   15.999O.pbe-van_ak.UPF
>>
>> Thanks & Regards,
>> Ajit,
>> IIT Madras, Chennai
>>
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Re: [Pw_forum] Spin-Orbit Calculation

[roberta pigliapochi]

Dear Ajit,
please bear in mind that I AM NOT AN EXPERT and I would instead really
appreciate comments from more experienced users. I will try to give some
advice but take it with a pinch of salt. I would also like to follow up on
this by asking:

can noncolinear calculations and DFT+U go together now?

Referring to your points:

1)the AFM initial guess is set up fine. The system might still converge to
a FM situation, though. If instead you'd rather force it to stay AFM I'd go
for 'tot_magnetization'
2)yes. You may also need to specify lda_plus_u=.true. beforehand.
3)I'd say so, and I also think that the 'angle' isn't a fixed value but
rather will be optimised during the scf. Instead if you'd prefer the two
(or total) magnetizations to be kept fixed along y I'd go for
'constrained_magnetization'
4)I think that the default 'domag' (whatever it means) is set to false,
hence there should be no need for your flag to be there. Also, 'nspin=4'
may be redundant considering that you have set 'noncolin=.true.'

hope some more hard-core expert will comment on this.

good luck (:
Roberta

Roberta Pigliapochi
PhD Student | Grey Research Group
University of Cambridge


On 8 September 2015 at 12:48, Ajit Kumar Jena  wrote:

> Dear All,
> I wish to do a *spin-orbit calculation* of our system
> (LiFePO4) which involves iron (Fe) as a magnetic element. Her*e *I am
> providing my input variables containing the system name lists and atomic
> species.
>
> My questions are the following :
>
> 1) As it is mentioned in the input, should I consider two different types
> of spins ( up and down ) to do a anti-ferromagnetic calculation ?
> 2) The way I have incorporated Hubbard 'U' is appropriate or not ?
> 3) If I am giving the inputs in this way, will it take the starting spin
> quantization axis along Y-direction or not ?
> 4) Is there any problem if i will not include " starting_spin_angle =
> .true. " ?
>
> Any kind of help is highly appreciated. I am extremely sorry if my
> questions are very trivial.
>
> *Input*
> 
> ibrav=  8,
> celldm(1) = 19.326236,
> celldm(2) = 0.587151,
> celldm(3) = 0.458766,
> nat=  28,
> ntyp= 7,
> !nspin = 4,
> starting_magnetization(2) = 0.7,
> starting_magnetization(3) = -0.7,
> ecutwfc =30.0,
> ecutrho = 250.0,
> occupations = 'smearing' ,
> degauss = 0.001 ,
> smearing = 'gaussian' ,
> noncolin = .true.
> lspinorb = .true.
> starting_spin_angle = .true.
> angle1(2) = 90.0
> angle2(2) = 90.0
> angle1(3) = 90.0
> angle2(3) = 90.0
> lda_plus_u_kind = 0,
> Hubbard_U(2)=3.0,
> Hubbard_U(3)=3.0,
>
> ATOMIC_SPECIES
>  Li1  6.94  Li.pbe-s-van_ak.UPF
>  Fe1  55.845Fe.rel-pbe-spn-rrkjus_psl.0.2.1.UPF
>  Fe2  55.845Fe.rel-pbe-spn-rrkjus_psl.0.2.1.UPF
>  P1   30.9737   P.pbe-van_ak.UPF
>  O1   15.999O.pbe-van_ak.UPF
>  O2   15.999O.pbe-van_ak.UPF
>  O3   15.999O.pbe-van_ak.UPF
>
> Thanks & Regards,
> Ajit,
> IIT Madras, Chennai
>
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[Pw_forum] Langevin dynamics

[Venkataramana Imandi]

Dear Dr. Xiaochuan Ge

Thank you for intimating particularly about time step in the Langevin
dynamics. I tried with 2.D0 (0.1 fs), however, system is exploding. I tried
according to your suggestion 0.2D0 (0.01 fs), it is working. I am asking
you is there any possibility to do Langevin dynamics at higher timestep
e.g. 0.1 fs or 0.2 fs. If there such type of possibility, please inform me
as soon as possible and what parameters i have to alter in the input file
for doing Langevin dynamics at higher time step.

Once again thanks for remembering me about Langevin dynamics is successful
at small time step.

Best
Venkataramana Imandi
PhD student
IIT Bombay


Dear Venkataramana,

I have some experience using the Langevin code. ?Before we go further to
understand your problem, I would suggest you to significantly lower the dt
and try again. Please try dt=0.2 instead of 20. If it still does not work,
please let me know.

Best,

===
Dr. Xiaochuan Ge (Giovanni)
Center for Functional Nanomaterials
Brookhaven national laboratory
===
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[Pw_forum] DOS Calculation

[Kanak Datta]

Dear researchers

I am facing problems in DOS calculation. I wanted to run the given example
in reference. I ran example 02 for this. The example is on bulk Ni. I ran
scf-> nscf and then went for dos.


outdir='D:\QuantumEspresso\Quantum ESPRESSO 64-bit 5.1.2-mpich2\ni'
prefix='ni'
fildos='ni.dos',
Emin=5.0, Emax=25.0, DeltaE=0.1
 /

I used dos.x package for this. However I am getting the following error:

 Error in routine dos (1):
 reading dos namelist

I can't figure out what's wrong. Can you help?
Thanks in advance.

Sincerely yours
Kanak
EEE, BUET
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